Many known computer-controlled operations on secured data files require verification of the identity of an individual seeking to access a file before the data (usually in encrypted form) can be accessed (see, for example, U.S. Pat. Nos. 3,938,091, 3,587,051, 3,611,293 and 4,198,619). In addition, many known record-securing schemes including those associated with credit cards, require verification of both the authority of the using individual and the authenticity of the data in the record, to protect against unauthorized users and against counterfeit or duplicate records. Schemes of this type are disclosed in U.S. Pat. Nos. 4,304,990, 4,328,414 and 4,357,429.
One disadvantage associated with computer-controlled security schemes of these types is that there is typically no indication left on file of which secured record was accessed, or by whom.